Lead-sharpener



Dec. 14, 1965 M. MAMlN LEAD-SHARPENER Filed April 28, 1964 United States Patent 2 Claims. (01. 120-91 The present invention has for its object a lead-sharpener including a closed casing, or support, constituted by a bellshaped body fitted over a base and provided with a socket through which extends a longitudinal passageway, the top of said socket being in the form of a sphere adapted to provide a ball-and-socket joint revolvably carried in an aperture of the upper wall of said body, said aperture being constituted by a border, said socket being adapted to receive a pencil, or mechanical propelling pencil, of which the lead is to be sharpened, whereby said lead is set in contact with a frusto-conical abrasive surface fitted at the bottom of the bell-shaped body, the bottom of the pencil sharpener being also provided with a frusto-conical protrusion coaxial with the last mentioned surface and adapted to guide the socket during its rotary movement.

Lead-Sharpeners of this type are already known, wherein the bell-shaped body and the socket are made of Bakelite.

Such apparatus have the drawback of breaking easily, chiefly when they fall on to the floor, which leads to a scattering of the graphite powder they contain.

In prior Ieadsharpeners, the spacing between the base of the casing and the bell-shaped body also produces an immediate scattering in the casing of the graphite dust, said base being constituted by a mere circular plate threaded into the bell-shaped body.

Again when such a pencil-sharpener is turned upside down, the powder contained therein may readily pass through a joint between the socket and the bell-shaped body.

The present invention meets all these drawbacks. To this end, the pencil-sharpener according to a preferred embodiment of the invention is provided with a base, the peripheral flange of which is force-fitted over the opening of the bell-shaped body, said flange being adapted to retain the graphite powder when the pencil-sharpener is being dismounted.

According to another embodiment of the present invention, the sphere at the top of the socket is force-fitted inside an elastic border secured to the bell-shaped body and matching the shape of said sphere over a fraction of its surface, said border preventing any graphite powder from flowing out of the pencil-sharpener along the periphery of the sphere when the pencil-sharpener happens to be turned upside down.

The pencil lead-sharpener according to the present invention is preferably made of a resilient thermoplastic material.

The construction and operation of the device forming the object of the present application will be fully disclosed hereinafter, reference being had to the accompanying drawing, in which FIG. 1 is a vertical cross-section of the lead-sharpener according to the invention, and

FIG. 2 is a plan view thereof.

As shown, the lead-sharpener includes a casing, or support, constituted by a bell-shaped body 1 and a base 2. A socket 4 extends through a central aperture 9 formed by a border 6 at the upper end wall 8 of body 1; it is provided with a passageway 3a adapted to receive a pencil 7 to be sharpened.

3,ZZ3,73 Patented Dec. 14, 1965 The top of said socket 4 is formed with a ball portion 3 to provide a ball-and-socket joint revolvably carried in the border 6, the inner surface of which accurately matches the outline of the ball corresponds to an equatorial segment portion of a sphere and which is thus locked but may rock freely inside said border. A stern portion 41) extends down from the ball portion 3.

The bell-shaped body 1 has outwardly the shape of an octagonal polyhedron, whereas its inner surface is cylindrical. The lower portion 1a of the bell-shaped body is perfectly cylindrical, both inside and outside.

Inside portion 1a of body 1 is housed a frusto-conical metal ring 5 lined by an abrading layer.

Ball-and-socket joint 3 is mounted by being urged through the restricted passage formed by the upper edge of border 6, upon resilient deformation of said border. However, once the joint 3 has been positioned, the border 6 sufficiently adheres to the joint 3 to prevent any graphite powder from being scattered in the event the sharpener is turned upside down.

The lower end of socket 4 is tapered at 4a so as to form a seat for the tip of the pencil, or mechanical propelling pencil, 7 introduced into passageway 3a.

When it is desired to sharpen the lead 7a of a pencil, or mechanical propelling pencil, the latter is caused to assume a conical movement about the center of joint 3, with its lead held in contact with the abrading ring 5 and it is caused to rotate around its longitudinal axis inside passageway 3a. This ensures the formation of a perfectly uniform conical tip on the lead.

In the present lead-sharpener, the slope to be given to a pencil during the sharpening operation is automatically obtained by reason of the particular shape given to the base 2 of the casing. In fact, the latter is provided, in its central portion, with a frusto-conical upper projection 2a, the apical angle of which is the same as that defined by the slope to be given to socket 4 during the sharpening operation, while the diameter of the lower end of said projection is such that said socket can be shifted only by a small angle, in a vertical plane. However, said possible vertical shifting is suflicient for rendering it possible to sharpen even the thickest pencil leads.

The projection 2a rises over the inner edge of the bottom annular portion 2b of base 2, while the outer edge of said portion 2b is provided with an upturned resiliently deformable cylindrical flange 20.

Base 2 is, as a matter of fact, made of a yielding plastic material, so that lower portion 1a of the body can be readily force-fitted inside the upper portion of the flange 2c of the base. An internal shoulder 2d limits entry of the body portion into the flange so that the lower edge of the body is spaced above the bottom of the flange.

The outer surface of base 2 is preferably faceted, and the bell-shaped body is preferably of a deformable thermoplastic material.

The base 2 actually constitutes a container for the graphite powder which is collected in the annular space 22 between the projection 2a and the lower portion of the flange 20, so that, when said bell-shaped body is being separated from base 2, the graphite powder cannot be scattered, as is the case with all prior lead-sharpeners.

The various parts forming the improved lead-sharpener according to the invention can be readily obtained through injection of plastic material into suitable molds, so that the apparatus disclosed can be speedily obtained and sold at a comparatively reduced price.

Of course, the present invention is not strictly limited to the above-disclosed form of embodiment, and changes of detail can be made therein without going beyond its scope. For instance, a hollow spherical cap may be secured under the base of the lead-sharpener and that (9 cap may be filled with ballast, so that the lead-sharpener can always return to its normal vertical position whenever it has been subjected to a violent shock, or when it has dropped onto the floor.

What I claim is:

1. A pencil-lead sharpener comprising a base having a bottom, a peripheral flange projecting upwardly from said bottom and a central circular projection extending up from the bottom and having a peripheral guiding surface; a bell-shaped body received in the upper portion of said peripheral flange of the base and fitting tightly therein, means limiting entry of said body into said flange so that the lower edge of said body is spaced upwardly from said bottom, said bell-shaped body having a top portion with a central aperture having an annual resilient lip and defining an equatorial segment of a spherical surface with upper and lower openings of smaller diameter than the iameter of said spherical surface, a socket extending through said aperture and comprising a spherical ball portion fitting closely and revolvably in said aperture and having a diameter greater than that of said upper and lower openings and being thereby retained in said aperture, and a hollow stem portion extending downwardly from said ball portion and having a longitudinal passageway adapted to receive a pencil, and an inwardly facing frustoconical abrasive surface inside a lower portion of said bell-shaped body above the lower edge thereof and coaxial with said aperture and said guiding surface, said stem portion being orbitally movable around and in engagement with said guiding surface and being guided by said guiding surface to move the lead of a pencil received in said passageway orbitally along said abrasive surface to sharpen said lead, a lower portion of said central projection of said base and a lower portion of said flange below the lower edge of said bell-shaped body defining an annular receptacle below the lower edge of said abrasive surface to receive pulverant material abraded from said lead, the close fit of said ball portion in said aperture preventing escape of said pulverant material from the top portion of said bell-shaped body in the event the sharpener is inverted.

2. A pencil-lead sharpener comprising a base having a bottom, a peripheral flange projecting upwardly from said bottom and having an internal shoulder intermediate its height defining upper and lower portions of said flange, and a central frustoconical projection projecting up from said bottom and forming a peripheral guiding surface; a bell-shaped body received in the upper portion of said flange of said base and seating on said shoulder, means releasably securing said body on said base, said bell-shaped body having a top portion with a central aperture having a resilient border and defining an equatorial segment of a spherical surface with upper and lower openings of smaller diameter than the diameter of said spherical surface, a socket extending through said aperture and comprising a spherical ball portion fitting closely and revolvably in said aperture and having a diameter greater than that of said upper and lower openings and being thereby retained in said aperture, and a hollow stem portion extending downwardly from said ball portion and having a longitudinal passageway adapted to receive a pencil, and an inwardly facing frustoconical abrasive surface inside a lower portion of said bell-shaped body above said shoulder and coaxial with said aperture and said guiding surface, said stem portion being orbitally movable around and in engagement with said guiding surface and being guided by said surface to move the lead of a pencil received in said passageway orbitally along said abrasive surface to sharpen said lead, a lower portion of said frustoconical projection and the lower portion of said flange below said shoulder defining an annular receptacle to receive pulverant material abraded from said lead the close fit of said ball portion in said aperture preventing escape of said pulverant material from the top portion of said bell-shaped body in the event the sharpener is inverted.

References Cited by the Examiner UNITED STATES PATENTS 5/1941 Dessonnaz 120-91 3/1960 Cunningham 120-91 FOREIGN PATENTS 245,104 10/1946 Switzerland.

EUGENE R. CAPOZIO, Primary Examiner. 

1. A PENCIL-LEAD SHARPENER COMPRISING A BASE HAVING A BOTTOM, A PERIPHERAL FLANGE PROJECTNG UPWARDLY FROM SAID BOTTOM AND A CENTRAL CIRCULAR PROJECTION EXTENDING UP FROM THE BOTTOM AND HAVING A PERIPHERAL GUIDING SURFACE A BELL-SHAPED BODY RECEIVED IN THE UPPER PORTION OF SAID PERIPHERAL FLANGE OF THE BASE AND FITTING TIGHTLY THEREIN, MEANS LIMITING ENTRY OF SAID BODY INTO SAID FLANGE SO THAT THE LOWER EDGE OF SAID BODY IS SPACED UPWARDLY FROM SAID BOTTOM, SAID BELL-SHAPED BODY HAVING A TOP PORTION WITH A CENTRAL APERTURE HAVING AN ANNUAL RESILIENT LIP AND DEFINING AN EQUATORIAL SEGMENT OF A SPHERICAL SURFACE WITH UPPER AND LOWER OPENINGS OF SMALLER DIAMETER THAN THE DIAMETER OF SAID SPERICAL SURFACE, A SOCKET EXTENDING THROUGH SAID APERTURE AND COMPRISING A SPHERICAL BALL PORTION FITTING CLOSELY AND REVOLVABLY IN SAID APERTURE AND HAVING A DIAMETER GREATER THAN THAT OF SAID UPPER AND LOWER OPENINGS AND BEING THEREBY RETAINED IN SAID APERTURE, AND A HOLLOW STEM PORTION EXTENDING DOWNWARDLY FROM SAID BALL PORTION AND HAVING A LONGITUDINAL PASSAGEWAY ADAPTED TO RECEIVE A PENCIL, AND AN INWARDLY FACING FRUSTOCONICAL ABRASIVE SURFACE INSIDE A LOWER PORTION OF SAID BELL-SHAPED BODY ABOVE THE LOWER EDGE THEREOF AND COAXIAL WITH SAID APERTURE AND SAID GUIDING SURFACE, SAID STEM PORTION BEING ORBITALLY MOVABLE AROUND AND IN ENGAGEMENT WITH SAID GUIDING SURFACE AND BEING GUIDED BY SAID GUIDING SURFACE TO MOVE THE LEAD OF A PENCIL RECEIVED IN SAID PASSAGEWAY ORBITALLY ALONG SAID ABRASIVE SURFACE TO SHARPEN SAID LEAD, A LOWER PORTION OF SAID CENTRAL PROJECTION OF SAID BASE AND A LOWER PROTION OF SAID FLANGE BELOW THE LOWER EDGE OF SAID BELL-SHAPED BODY DEFINING AN ANNULAR RECEPTACLE BELOW THE LOWER EDGE OF SAID ABRASIVE SURFACE TO RECEIVE PULVERANT MATERIAL ABRADED FROM SAID LEAD, THE CLOSE FIT OF SAID BALL PORTION IN SAID APERTURE PREVENTING ESCAPE OF SAID PULVERANT MATERIAL FROM THE TOP PORTION OF SAID BELL-SHAPED BODY IN THE EVENT THE SHARPENER IS INVERTED. 